1. Field of the Invention
The present invention relates to a charged-particle beam lithographic apparatus and a method of manufacturing a device using the same.
2. Description of the Related Art
A charged-particle beam lithographic apparatus that draws a pattern on a substrate using a charged-particle beam such as an electron beam or an ion beam is known. Japanese Patent Laid-Open No. 61-020321 discloses an electron beam exposure apparatus, in which an electrode is inserted into a column and a radio frequency or high frequency voltage is applied across the electrode and the inner wall of the column to generate a plasma in the column, thereby removing any substances adhering on the inner wall surface of the column using the plasma. Japanese Patent Laid-Open No. 08-139010 discloses a charged beam apparatus, in which a plasma is generated by a plasma generating device arranged outside a barrel, and introduced into the barrel, thereby removing any contaminants.
In the charged-particle beam lithographic apparatus, when an aperture plate having apertures is present in the path through which an active species (radicals fall into the concept of the active species) flows, the conductance of the portion where the aperture plate is placed is low so the active species is inactivated, thus making it impossible to satisfactorily clean the interior of the apertures. When the amount of gas for generating an active species is increased so as to increase the amount of active species, the pressure in the chamber rises. Then, the time required to reduce the pressure in the chamber after the end of cleaning prolongs, so the downtime may prolong.